The proposed project will develop a nonhuman primate model of psychosocial influences on disease progression in acquired immune deficiency syndrome (AIDS). In humans, the quality and stability of social life have been implicated as important factors in the progression of diseases such as cancer and cardiovascular disease. HIV disease is often associated with social disruption, and preliminary evidence suggests and psychosocial factors may be related to the progression of HIV infection. Inoculation of rhesus macaques with the simian immunodeficiency virus (SIV) produces a disease considered by many (e.g., IOM, WHO) to be one of the best animal models of HIV infection in humans. Moreover, because of their highly social nature, parallels in psychosocial processes exist between rhesus macaques and humans as well. In the proposed research, we will 1) examine the effects of social stress (i.e., stability/instability of social groups) on behavioral, neuroendocrine, and in vivo measures of immune system functioning in adult male rhesus macaques; and 2) examine the interrelations of these processes in the presence and the absence of concurrent infection with a cloned variant of SIV. By so doing, we will obtain what we believe are the first data on whether a psychosocial intervention can affect the course of an infectious disease in a nonhuman primate. An animal model of the relationship between social stress and disease progression in simian AIDS, involving controlled experimental manipulation, will provide important basic information on the interrelations of social experience and physiological functioning. Such a model is also likely to provide clinically valuable information in the treatment of individuals diagnosed as HIV positive.